It is well known in the art that an initial guided angle (pre-tilt angle) of liquid-crystal molecules is determined by an alignment film in a LCD panel. The liquid-crystal molecules are aligned generally by means of a rubbing process for the alignment film. However, since the rubbing process is not easily manipulated, the process of the alignment film requires to be controlled accurately. Therefore, a photo-alignment technique utilizing polymers has been proposed to solve the drawback of the above-mentioned rubbing alignment.
In general, a photo-alignment technique requires blending reactive monomers into an LC layer and applying a predetermined voltage thereto by a voltage applying device. The LC layer is irradiated by ultraviolet (UV) light under the predetermined voltage. The reactive monomers are then polymerized and cured forming a polymer layer simultaneously on substrates at opposite sides of the LC layer.
Referring to FIG. 1, FIG. 1 is a top view schematically illustrating a conventional voltage applying device applying voltage on an active device array substrate. The active device array substrate 10 which performs the photo-alignment has a plurality of pixel array areas 120. Each pixel array area 120 is coupled to an external voltage applying device 20 via curing lines 142 and corresponding curing pads 144 outside the pixel array area 120. The applied predetermined voltage is transmitted through probe pins (not shown) of the voltage applying device 20 and electrically contacting the curing pads 144, and then the voltage is transmitted to the pixel array areas 120 via the curing lines 142.
However, the probe pins are held by a probe bar 210 (as shown by dashed lines for clarity), and the probe bar 210 is fixed by locking the probe bar 210 onto hole positions 221 of the base 220 around the substrate 10 in the conventional voltage applying device 20. Thus, the probe bar 210 is fixed on the base 220 and can not be adjusted arbitrarily, and a pitch of the probe pins is also fixed. When performing the photo-alignment for substrates of various sizes, different voltage applying devices are needed to correspond thereto due to different positions of the curing pads thereon and different pitches therebetween. It can be seen from FIG. 1 that the voltage applying device requires disposing around the active device array substrate 10. Therefore, multiple voltage applying devices are needed to be bought, this results costs increase. Moreover, in time of replacing the voltage applying devices, there requires manpower to disassemble, and the probe pins can easily be damaged. This should add costs to production.
In summary, the problem that the voltage applying device can not correspond to various LCD substrates for causing increased costs in the prior art needs to be solved.